The duo Rodrigo y Gabriela make it abundantly clear that rocking out on acoustic guitars is very possible. Rodrigo Sanchez and Gabriela Quintero met in their native Mexico City, then honed their act during a multi-year residency in Dublin, Ireland. They now tour all around the globe — they last came to New Orleans for the 2012 Jazz Fest — blowing audiences away with their especially aggressive style of classical guitar fireworks.

Reinvented rock songs often find their way into Rodrigo y Gabriela's repertoire. Metallica anthems are a particular favorite. So it was a big moment when, on Aug. 17, Metallica bassist Robert Trujillo joined Rodrigo y Gabriela onstage at Red Rocks Amphitheater outside Denver, Colo.

Trujillo laid down bass for a Metallica medley that included "Orion," "For Whom the Bell Tolls," "The Frayed Ends of Sanity" and "Battery." Midway through the 13-minute medley, he's assumed the trademark predatory crouch he often uses with Metallica, an indication that he's into it.